Helical spline torque indicator



June 29, 1948. P. P. NEWCOMB 2,444,363

HELICAL sums TORQUE mnIcA'roR Filed Aug. :50, 1944 2 Sheets-Sheet 1 Z2INVENTOR.

ATTORJS/EY June 29, 1948. P. P. NEWCOMB 2,444,363

HELICAL SPLINE TORQUE INDICATOR Filed Aug. 30, 1944 2 Sheets-Sheet 2 VEN TOR.

Patented June 29, 1948 nation. sruua 'ronous rumca'roa Philip PntneyNewoomb, Manchester, Conn" assignor to United Aircraft corp ration, EastHartford, coma. a corporation of Delaware Application August :0, m4,Serial No. sums 8 Claims. (Ci. vs-isti This invention relates to torqueindicators or meters and has for its object to provide a novel andimproved device of this type for giving a continuous reading of thetorque to which an aircraft engine or other mechanism is subjected.

Another object of the invention is to provide a torque indicator whichis simple in construction, efhcient in operation, and is considerablylighter and less bulky than previous devices of this type.

Another object is to provide a torque indicator of the foregoing typehaving novei'and improved details of constructionand features ofoperation.

Various other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed.

Although the invention is useful in many dlfferent situations in themechanical arts, I shall illustrate it in its application to an airplaneengine having a planetary reduction gear between the engine crankshaftand the propeller shaft, in which type of power plant economy of sizeand weight are of paramount importance.

In one such installation, hereinafter described, the "stationary"reaction member of the planetary reduction gear train is secured to thereduction gear housing by means of a special helical spline concentricwith the axis of the gear. The reaction torque of the stationaryreaction member causes said member to turn and advance along the helix.The thrust so produced is resiliently restrained by one or morehydraulic devices containing oil or other fluid under pressure, and thepressure exerted in the hydraulic line, which may be registered on asuitable metenis a measure of the torque exerted by the engine.

Although the novel features which are characteristic if this inventionare set forth more in detail in the claims appended hereto, the natureand scope of the invention may be better understood by referring to thefollowing description, taken in connection with the accompanyingdrawings forming a part thereof, in which certain specific embodimentshave been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a longitudinal sectional view through the nose section of anairplane engine, showing the application thereto of a torque indicatingmechanism embodying the invention; 3

Fig. 2 is an enlarged sectional view of a portion of Fig. 1, showingdetails of the hydraulic metering system;

Fig. 3 is a fragmentary sectional view illustratmg a modification or theinvention; and

Fig. 4 is a similar view illustrating the co struction of the splines onthe reaction gear employed in Fig. 3.

In the following description certain specific terms are used forconvenience in referring to the various details of the invention. Theseterms, however, are to be interpreted as broadly as the state of the artwill permit.

In Figs. 1 and Ian internal combustion engine ordinarily employed forthe propulsion of aircraft is represented as comprising a crankcase inground or along which are arranged a plurality of cylinders l2containing pistons it which are connected to the crankshaft ll in theusual manner.

From the nose section Ii, which is secured to the crankcase, projectsthe propeller shaft It carrying an aeronautical propeller, not shown.The propeller shaft I6 is connected to the engine crankshaft II by aplanetary reduction gear which will now be described.

The reduction gear mechanism of Fig. 1 includes a suitable sun gear i8drivingly connected to the crankshaft, and a rotatable cage i 9drivingly connected to the propeller shaft and carrying planet gears 20which mesh with the external gear teeth of the sun gear l'l and with theinternal gear teeth of a relatively fixed reaction gear.

As shown in Figs. 1 and 2, the external periphery of the reaction gear2| is provided with helical splines 22 meshing with correspondinghelical splines 23 on the interior flange 24 of the engine casing. Whenthe engine is operating, the reaction torque of the relatively fixedgear 2 I, tending to rotate said gear, causes same to move sidewaysalong the path prescribed by the helical 28 having a shaft 2! bearing onthe face of gear 2|, as best shown in Fig. 2. The system illustratedherein employs a plurality of such hydraulic devices, although only oneis shown for the sake of simplicity.

The hydraulic system contains oil under pressure, derived from theengine lubricating system and supplied to the cylinder 25 from annularchannel 29 in crankcase I! through valve ports 30 leading to the hollowinterior of the piston shaft 21. The channel 28 communicates with ports3! in the shafts-21 of all the pistons 28, and serves to equalize thepressure among the various Ill concentric with the bellows 52.

pistons. The hydraulic cylinder is connected by duct 32 to a, suitablemeter 33 adapted to register variations in thepressure exerted in thetrue of the arrangement shown, because ports 3!] are closed off as theoil is admitted and the piston 28 is forced thereby to the right in Fig.2 against the helically splined gear 2|. As the oil leaks from thecylinder 25, the piston 26 will be forced to the left until ports areuncovered to inlet channel 29 which will admit oil to the cylinder andagain force the piston to the right to cut off the supply of oil, asdescribed above. With this arrangement, it is of course necessary thatthe inlet pressure in the channel 29 be sutliciently great to overcomethe force exerted on the piston 28 by the helically splined gear 2|.

It will be evident from the above that the pressure of the pi] in thecylinder 25 is proportional to the reaction torque which, in .turn, isproportional to the torque of either the driven or the driving shaft ofthe reduction gear. Thus the torque exerted by the engine is indicatedon the meter 33. As shown in Figs. 1 and 2, the antithrust side of thestationary flange 24 of the crankcase is provided with an annular backplate 35 to limit the backward movement of reaction gear 2! under thepressure of the hydraulic sysj tem.

Figs. 3 and 4 show a modification of the invention in which therelatively fixed reaction gear (corresponding with gear 2| of Figs. 1and 2) is composed of two annular sections 31 and 38 having identicalaligned internal gear teeth meshing with the planet gears 20, and havingexternal helical splines 39 and 40, respectively, which slope inopposite directions in the manner of a socalled herringbone pattern.These splines 39 and 40 mesh with corresponding splines 4| and 42 on theinterior flange 24 of the engine casing,

the said splines 4| and 42 being separated by a groove 43 which isformed on the inner surface of flange 24 to facilitate machining of saidsplines.

The annular reaction gear sections 31 and 38 have internal annularrecesses 41 and 48 facing each other, and within these recesses areseated .two pairs of spaced concentric bands 49 and 50 p which aresecured to the internal flanges of the respective gear sections 31 and38,,as shown in Fig. 3. An annular bellows type seal 52 is secured tothe two bands 49, and a similar annular bellows 53 of larger diameter issecured to the two bands The two concentric bellows 52 and 53 thus sealthe annular space or chamber which exists within the gear sections 31and 38. This sealed chamber is connected through an inlet valve 54 tothe oil duct 28 leading to the engine lubricating system, and to duct 32leading to the torque meter 33.

When the engine is operating, the reaction torque exerted upon therelatively fixed gear sections 31 and 38 causes said sections to turnand advance along the respective helical splines 4| and 42, saidsections 31 and 38 moving either toward or away from each otheraccording to the force exerted thereon. As in the embodiment 4 apreviously described, the torque exerted by the engine isregistered onthe meter 33.

Although certain specific embodiments of the invention have been shownfor purposes of illustration it is to be understood that the inventionis capable of various modifications and adaptations which will bereadily apparent to a person skilled in the art. The invention is onlyto be limited in accordance with the scope of the appended claims.

The invention claimed is:

1. In a power transmission system, a planetary gear train including arelatively fixed reaction gear subject to reaction torque, a stationarymember containing helical spiines, corresponding helical splines on saidgear meshing with those on said stationary member whereby torque tendingto rotate said gear will move said gear in the helical course of saidsplines, means yieldingly restraining the helical movements of saidgear, and indicating means connected to said yielding means andresponsive to the movement of said gear.

2 In a power transmission system, a planetary gear train including arelatively fixed reaction gear subject to reaction torque, a stationarymember containing helical splines, corresponding heli cal splines onsaid gear meshing with those on said stationary member to move said gearin the helical course of said splines upon the application of torquetending to rotate said gear, means resiliently restrainlngthe helicalmovement of said gear, and torque indicating means actuated by saidrestraining means.

3. In a power transmission system, a planetary gear train including arelatively fixed reaction gear subject to reaction torque, a stationarymember containing helical splines, corresponding helical splines onsaidgear meshing with those on said stationary member'to-move said gear inthe heli cal course of said splines upon the application of torquetending to rotate said gear, means including a hydraulic piston actingon said gear to restrain the helical movement thereof, a hydraulic fiuidunder pressure acting on said piston, and torque indicating meansactuated by said fluid.

4. In a power transmission system, a planetary gear train including apair of relatively fixed reaction gear sections subject to reactiontorque, helical splines on said gear sections sloping in oppositedirections, a stationary member having corresponding sets of helicalsplines meshing with those on the respective gear sections to guide saidgear sections in the helical courses of said splines upon theapplication of torque, means including a fluid under pressurerestraining the force of the torque upon said gear sections, and torqueindicating means actuated by said fiuid.

5. In a power transmission system, a planetary gear train including apair of relatively fixed reaction gear sections having internal annularrecesses in their adjacent faces, concentric annular bellows in saidrecesses sealing same into a common annular chamber for the reception ofa hydraulic fluid, helical splines on the outer periph- 5 driving memberand a driven member, a planetary gear system coupling said driving anddriven members comprising a reaction gear, helical splines on theexterior of said reaction gear, a

fixed member carrying splines engaging the splines on the reaction gear,said splines on the gear and fixed member cooperating to shift the gearlaterally of the fixed member upon the application oi torque tending torotate said gear, a hydraulic piston actuated by said shifting of thereaction gear, means controlled by the gear for supplying fluid underpressure to the working face of the piston, and indicating meansresponsive to pressures applied to the fluid by the piston.

7. An apparatus for indicating torque in a reduction gear traincomprising a driving gear, a reaction gear, planet gears meshing withthe driving gear and the reaction gear, means comprising helical splinesfor eflecting an axial movement of the reaction gear and for restrainingsaid gear go 1,533,602

against rotation when torque is appliedthereto by the planet gears, ahydraulic system comprising a fluid pressure responsive member directlyin contact with a side of the reaction gear whereby said hydraulicsystem will yieldingly limit the axial movements of the reaction gear,and a torque indicator operatively connected to the hydraulic system. H

8. In a power transmission system, a planetary gear train including apairoi co-axial gear sec- 30 tions subject to torque, helical teeth onsaid gear 1o tuated by said fluid pressure.

PHILIP PUTNEY NEWCOBIB.

REFERENCES CITED The following references are ofrecord in the i6 file ofthis patent:

UNITED STATES PATENTS Number Name Date 389,928 Hurdle et a1. Sept. 25,1888 Midgley June 15, 1926 2,297,644 Angst Sept. 29, 1942 2,353,814 DePew July 18, 1944 2,386,367 Taylor Oct. 9, 1945 2,388,204 Barnes Oct.30, 1945 3 2,289,285 Chilton July '1, 1942 FOREIGN PATENTS NumberCountry Date 5,804 Great Britain 1909 174,726-

' Great Britain Jan. 30, 1922

